Researchers at Imperial College London claim to have developed technology that would enable the creation of three-dimensional microchips, which will dramatically increase their memory capacity. According to their press release:
"by using nanotechnology it is possible to reproduce the key functions of semiconductor electronics in microchips using only the 'spin' of electrons, which is responsible for magnetism, rather than the more conventional 'charge' that traditional microchips use."

Particularly, does it hold it's memory reliably without power? And how does it compare speed-wise to current day ram?

It would be kind of interesting if the fastest storage space available was also the cheapest and didn't need power. You'd be looking at a fundamental change in the storage hierarchy of computers! I'm probably over-imagining things here though